Scanning tunneling microscopy contrast of isovalent impurities on the GaAs (110) surface explained with a geometrical model

Tilley, F J; Roy, Mervyn; Maksym, P. A.; Koenraad, PM Paul; Krammel, CM Christian; Ulloa, JM José Maria

doi:10.1103/physrevb.93.035313

Cited by 12 publications

(25 citation statements)

References 30 publications

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“…This geometrical interpretation can be seen as an experimental confirmation and extension of the theoretical work of Tilley et al in Ref. [19] on the structural modification of the (110) GaAs surface by isovalent dopants from groups III and V. There, it has been shown that the relaxed position of isovalent impurities in the (110) surface depends on the effective size of the involved elements. Bigger/smaller atoms than the ones they are replacing relax into a position above/below the surface, which leads to atomiclike bright/dark contrasts in STM measurements.…”

Section: A Classification Of the Main Bi Related Featuressupporting

confidence: 64%

“…We have shown that the contrast observed in the X-STM measurements taken at a high sample voltage can be understood by considering the geometry of the relaxed (110) surface which, in turn, is determined primarily by the difference in effective size of the Bi dopant compared to the In and P atoms. Bi is the largest stable group-V element and, using this geometrical model [19], we therefore predict similar contrast in any Bi-doped III-V compound with a zinc-blende structure.…”

Section: Discussionmentioning

confidence: 97%

“…126-atom supercells with a 3 × 3 surface periodicity were used, with a cutoff energy for the plane-wave basis set, E cut , of 30 Ry and a 4 × 4 × 1 k grid [19]. The supercells are separated by a 12-Å vacuum gap and the system was allowed to fully relax with a tolerance on the forces of 1 × 10 −4 hartrees per bohr.…”

Section: Density Functional Theory Calculationsmentioning

confidence: 99%

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Incorporation of Bi atoms in InP studied at the atomic scale by cross-sectional scanning tunneling microscopy

Krammel

Roy

Tilley

et al. 2017

Phys. Rev. Materials

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We show the potential of cross-sectional scanning tunneling microscopy to address structural properties of dilute III-V bismides by investigating Bi:InP. Bismuth atoms down to the second monolayer below the {110} InP surfaces, which give rise to three classes of distinct contrast, are identified with the help of density functional theory calculations. Based on this classification, the pair-correlation function is used to quantify the ordering of Bi atoms on the long range. In a complementary short-ranged study, we investigate the Bi ordering at the atomic level. An enhanced tendency for the formation of first-nearest-neighbor Bi pairs is found. In addition, the formation of small Bi clusters is observed whose geometries appear to be related to strong first-nearest-neighbor Bi pairing. We also identify growth related crystal defects, such as In vacancies, P antisites, and Bi antisites.

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Section: A Classification Of the Main Bi Related Featuressupporting

confidence: 64%

Section: Discussionmentioning

confidence: 97%

Section: Density Functional Theory Calculationsmentioning

confidence: 99%

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Incorporation of Bi atoms in InP studied at the atomic scale by cross-sectional scanning tunneling microscopy

Krammel

Roy

Tilley

et al. 2017

Phys. Rev. Materials

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“…1(a)]. Dark contrast features have been observed for nitrogen in X-STM in the past with filled state imaging [45][46][47][48] and have been reproduced in theoretical models [51,52]. The observation of dark contrast is attributed to a depression at the surface caused by the shortened bonds between the nitrogen and its neighboring Ga atoms.…”

Section: Resultsmentioning

confidence: 72%

“…Tilley et al [52] calculated that the nitrogen atoms in those positions displace multiple arsenic atoms in the surface.…”

Section: Resultsmentioning

confidence: 99%

Spatially resolved electronic structure of an isovalent nitrogen center in GaAs

et al. 2017

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Small numbers of nitrogen dopants dramatically modify the electronic properties of GaAs, generating very large shifts in the conduction-band energies with nonlinear concentration dependence, and impurity-associated spatially-localized resonant states within the conduction band. Cross-sectional scanning tunneling microscopy provides the local electronic structure of single nitrogen dopants at the (110) GaAs surface, yielding highly anisotropic spatial shapes when the empty states are imaged. Measurements of the resonant states relative to the GaAs surface states and their spatial extent allow an unambiguous assignment of specific features to nitrogen atoms at different depths below the cleaved (110) surface. Multiband tight binding calculations around the resonance energy of nitrogen in the conduction band match the imaged features. The spatial anisotropy is attributed to the tetrahedral symmetry of the bulk lattice. Additionally, the voltage dependence of the electronic contrast for two features in the filled state imaging suggest these features could be related to a locally modified surface state.

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Structural Properties of Bi Containing InP Films Explored by Cross-Sectional Scanning

Krammel

Koenraad

Roy

et al. 2019

Bismuth-Containing Alloys and Nanostructures

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Scanning tunneling microscopy contrast of isovalent impurities on the GaAs (110) surface explained with a geometrical model

Cited by 12 publications

References 30 publications

Incorporation of Bi atoms in InP studied at the atomic scale by cross-sectional scanning tunneling microscopy

Incorporation of Bi atoms in InP studied at the atomic scale by cross-sectional scanning tunneling microscopy

Spatially resolved electronic structure of an isovalent nitrogen center in GaAs

Structural Properties of Bi Containing InP Films Explored by Cross-Sectional Scanning

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